References UK clinical guidance from the NHS, the British HIV Association (BHIVA), and the British Association for Sexual Health and HIV (BASHH). Last updated: April 2026.
STI symptoms can appear anywhere from 2 days to 3 months after sex, depending on the infection. Some STIs show symptoms within a week. Others take weeks or months. And many produce no symptoms at all, which is why testing is more reliable than waiting to feel unwell.
If you’ve recently had unprotected sex and you’re watching for signs, this guide covers the symptom timeline for every major STI, plus when to get tested for the most accurate results.
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STI Symptom Timeline: When Do Signs Appear?
| STI | Symptoms Appear | % Asymptomatic | Testing Window |
|---|---|---|---|
| Chlamydia | 1-3 weeks | 70% women, 50% men | From 2 weeks |
| Gonorrhoea | 1-14 days | Up to 50% women, 10% men | From 2 weeks |
| Genital herpes | 2-12 days | Many never have outbreaks | Swab during outbreak; blood test from 12 weeks |
| Syphilis (primary) | 10-90 days | Chancre can be painless/hidden | From 4-6 weeks |
| HIV (acute) | 2-4 weeks | 20-40% have no acute symptoms | From 4 weeks (conclusive at 90 days) |
| HPV / genital warts | Weeks to months | Most infections: no warts | No routine test for men; cervical screening for women |
| Trichomoniasis | 5-28 days | Up to 70% | From 2 weeks |
| Hepatitis B | 6-12 weeks | Up to 50% | From 6 weeks |
| Mycoplasma genitalium | 1-5 weeks | Many asymptomatic | From 2 weeks |
Chlamydia: 1-3 Weeks
When symptoms appear, they usually show up within 1-3 weeks. But the majority of chlamydia infections, around 70% in women and 50% in men, cause no symptoms at all. You can carry chlamydia for months or years without knowing.
When present, symptoms include unusual discharge, pain when urinating, and in women, bleeding between periods. In men, mild discharge and a burning sensation are the most common signs.
Read more: What is chlamydia? | How long can chlamydia stay dormant?
Gonorrhoea: 1-14 Days
Gonorrhoea symptoms tend to appear faster than chlamydia, often within a few days. Men usually notice symptoms more readily: thick yellow or green discharge and significant pain when urinating. Women may have milder symptoms or none at all.
Throat and rectal gonorrhoea are often completely symptom-free and only detected through screening.
Genital Herpes: 2-12 Days
A first herpes outbreak typically appears 2-12 days after exposure. It starts with tingling or itching, followed by small blisters that break open into painful sores. The first outbreak is usually the most severe and can include flu-like symptoms.
Some people have very mild first outbreaks that they barely notice. Others never have a recognisable outbreak despite carrying the virus. Herpes can also reactivate weeks, months, or years later.
Syphilis: 10-90 Days
The first sign of syphilis is a painless sore (chancre) at the site of infection. This can appear anywhere from 10 to 90 days after exposure. The sore is often painless and in a location that’s hard to see (inside the vagina, rectum, or throat), which is why it’s frequently missed.
The chancre heals on its own within 3-6 weeks, but the infection progresses to secondary syphilis, which can cause rashes, sore throat, and flu-like symptoms weeks later.
HIV: 2-4 Weeks (Acute Symptoms)
Around 60-80% of people experience flu-like symptoms 2-4 weeks after contracting HIV. This is called seroconversion illness, and it typically includes fever, sore throat, rash, fatigue, and swollen glands. Symptoms last 1-2 weeks and then resolve.
After this, HIV enters a latency period where there are often no symptoms for years. This is why testing is the only reliable way to know your status.
Read more: HIV symptoms in women | What is HIV?
The Problem with Waiting for Symptoms
Waiting to see if symptoms appear is not a reliable strategy for several reasons:
- Most STIs can be asymptomatic — you can be infected and infectious without any signs
- Symptoms can be mild or mistaken for something else — a slight sore throat could be gonorrhoea. Mild discharge could be chlamydia.
- Some symptoms are delayed by months — syphilis and hepatitis B can take weeks to months to show
- By the time symptoms appear, complications may have started — chlamydia can damage fallopian tubes before you notice any pain
If you’ve had unprotected sex with a new partner, the best approach is to get tested at the right time, not to wait and watch.
When to Get Tested
Different tests have different windows. Here’s when to test for the most reliable results:
- Chlamydia and gonorrhoea: From 2 weeks after exposure
- Syphilis: From 4-6 weeks
- HIV: From 4 weeks (a negative result at 90 days is conclusive)
- Herpes: Swab during an active outbreak anytime; blood test reliable from 12 weeks
- Hepatitis B: From 6 weeks
If you test within the window period and get a negative result, consider retesting after the full window has passed for complete certainty.
Order a comprehensive home STI test kit or find your nearest sexual health clinic.
Frequently Asked Questions
Can STI symptoms appear the next day?
It’s extremely unlikely for any STI to cause symptoms within 24 hours. The fastest-appearing STI is genital herpes, which can show symptoms from 2 days after exposure. If you experience symptoms the next day, they’re more likely caused by irritation, an allergic reaction, or a pre-existing condition.
I had unprotected sex a week ago and feel fine. Am I in the clear?
Not necessarily. Many STIs take 2-4 weeks to show symptoms, and many never cause symptoms at all. Feeling fine doesn’t mean you’re not infected. Get tested from 2 weeks onwards for the most common infections.
Can stress cause STI-like symptoms?
Stress can trigger herpes outbreaks in people who already carry the virus. It can also cause general symptoms like fatigue, body aches, and digestive issues that might feel like an STI. However, symptoms like unusual discharge, sores, or pain urinating should always be checked rather than attributed to stress.
How long can an STI go undetected?
Some STIs can go undetected for years. Chlamydia can be carried asymptomatically for months to years. HIV can be asymptomatic for a decade. Syphilis has a latent stage that can last years. Regular testing is the only reliable way to catch these infections.
Related reading
- Cold Sores vs Syphilis Sores: How to Tell the Difference
- Do STIs Always Have Symptoms?
- How Different STIs Affect Vaginal Discharge
- How to Identify Syphilis Sores (Chancres)
- Is My Rash From HIV or Something Else?
Sources
- NHS — Sexual health conditions
- BASHH — UK clinical guidelines for STI management
- British HIV Association (BHIVA) — HIV treatment guidelines
- Terrence Higgins Trust — sexual health information
- UK Health Security Agency — STI surveillance data
Steve Page is a recognised expert on Sexually Transmitted Diseases (STDs) and STD treatments, having published numerous articles in peer-reviewed journals and presented his research at conferences around the world. He has an in-depth understanding of the latest medical research on STDs, and is an advocate for the development of new treatments and protocols to improve the health of those affected. In addition to his research, he has dedicated his career to understanding the causes and symptoms of STDs, as well as how to best treat those impacted.
